The generation of narrow pulses occurs in a variety of fields including ultra-wideband (UWB) radios/radars and “Clock Data Recovery” (CDR) circuits. For example, ultra-wideband radios transmit information using narrow pulses with very small duty cycles. In this fashion the signal spectrum extends over a large bandwidth and can be buried in the ambient noise in a way that does not interfere with other services. Another important application of narrow pulses is in CDR circuits which retime the received data and remove the jitter accumulated during data transmission. For example, the random binary data obtained by optical receivers can not provide any direct information about the clock since it contains no spectral line at the bit rate. To create a frequency component at the bit rate, the data must undergo differentiation and rectification, which is also called “edge detection”. To realize differentiation and rectification in CDR integrated circuits, it is necessary to create short pulses during each data transition.
In general, the narrower the pulse that is generated, the more “ultra-wideband” is the resulting signal spectrum. Current state-of-the-art pulse generators are considered ultra-wideband with pulse widths in the hundreds of pico-seconds. But for certain high-frequency data transmission applications, such a pulse width is too broad. Moreover, an UWB radar increases its range resolution as the pulse width is narrowed.
Accordingly, there is a need in the art for improved UWB pulse generators.